Class 8 Science Chapter 2 MCQ

Robert coach is known for his role in identification of the causing agent of Anthrax. Edward Jenner is known as father of immunology. He discovered the vaccine for smallpox in 1798. Louis Pasteur discovered fermentation in 1857 by demonstrating the microbes cause souring of milk.

Virus is a micro-organism, which is in an inactive or dead from outside the body of a host. It reproduces or replicates only when it enters a host and reaches its cells.

Paramecium is a unicellular organism, a protozoan found in water bodies. Spirogyra is a filamentous green spiral in shape, ground as green slimy mats on surface of water bodies. Penicillin antibiotic is extracted from aspergillus fungi.

Communicable diseases can spread from infected person to others when any person cough or sneeze. When a person suffering from common cold sneezes, fine droplets of moisture carrying thousands of viruses are spread in the air. The virus may enter the body of a healthy person while breathing. It can spread by street food also.

Influenza is an infectious disease caused by the influenza virus. It is also known as flu symptoms include high fever, running nose, sore throat, headache, coughing and muscles pain etc. Typhoid, dysentery and cholera are bacterial infections.

Here, all the statements are correct. Hence, your answer will be option [D].

Antibiotics are substances that may inhibit or kill the growth of different microbes. Microorganisms causing infection in host bodies are killed by consumption of these antibiotics.

Spirogyra is multi-celled algae. Chlamydomonas and diatoms are single-celled algae. Blue-green algae can fix nitrogen gas of atmosphere.

In 1975 John Bartlett, the discovery of Clostridium difficile and he identified it as the leading cause of hospital-associated infections. Tetanus is caused by a toxin made by spores of bacteria, Clostridium tetani, found in soil, dust and animal feces. When the spores enter a deep flesh wound, they grow into bacteria that can produce a powerful toxin, tetanospasmin. The toxin impairs the nerves that control your muscles (motor neurons).

Here, all the options are correct. Hence, your answer will be option [D].

Lichens is an association between fungal and an algal species. It is a mutually benefiting association where algae provide food to the fungus and in return gets shelter from it.

Here, all the options are correct. Hence, your answer will be option [D].

Antibiotics should be taken only on the advice of “Qualified Doctor”. Qualified doctor means a person who is legally qualified to practice medicine; doctor of medicine. In the other words, a person who engaged in general medical practice, as distinguished from one specializing in surgery.

Carbon dioxide is released during the preparation of bread. This is the process of fermentation in which yeast cells rapidly produces CO2, which causes risening of the dough used in preparation of bread.

Female Anopheles mosquito which carries the parasite of malaria. Female Aedes mosquito acts as carrier of dengue virus. Malaria is caused by the protozoan parasite Plasmodium.

Malaria is the disease which is caused by the spread of a “Protozoan” i.e. “Plasmodium”. It is spread in healthy individuals by the bite of a female “Anopheles Mosquito” caring this “Plasmodium” in their mouth (saliva).

Bacillus anthracis is an aerobic spore-forming bacterium that causes disease in humans and animals. The bacteria is found in two forms: cutaneous anthrax and inhalation anthrax. Cutaneous anthrax is an infection of the skin caused by direct contact with the bacterium.

We should avoid eating uncovered food items. Rest of all are correct. Hence, your answer will be option [A].

Malaria is not caused by a virus or bacteria. Malaria is caused by a parasite known as Plasmodium, which is normally spread through infected mosquitoes. A mosquito takes a blood meal from an infected human, taking in Plasmodia which are in the blood. Ronald Ross is famous for his work concerning malaria and was awarded the Nobel Prize for Physiology or Medicine in 1902. He discovered that the salivary gland in the mosquito was the storage site of malarial parasites and using infected birds, he demonstrated the full life cycle of the malarial parasitic organism

Housefly carries the disease-causing microbes’ outside of its body. Mosquito carries microbes inside its body. Anopheles mosquito carries the plasmodium parasite of malaria.

Streptomycin is the antibiotics but hemocyanin is a protein found in mollusks that carries oxygen in much the same way as hemoglobin carries oxygen in human blood. Antibiotics are effective to control disease in plants and animals.

Allergic bronchopulmonary aspergillosis (ABPA) is a condition characterized by an exaggerated response of the immune system (a hypersensitivity response) to the fungus Aspergillus fumigatus.

Antibiotics should be taken only on the advice of “Qualified Doctor”. Qualified doctor means a person who is legally qualified to practice medicine; doctor of medicine. In the other words, a person who engaged in general medical practice, as distinguished from one specializing in surgery.

In 1975 John Bartlett, the discovery of Clostridium difficile and he identified it as the leading cause of hospital-associated infections. Tetanus is caused by a toxin made by spores of bacteria, Clostridium tetani, found in soil, dust and animal feces. When the spores enter a deep flesh wound, they grow into bacteria that can produce a powerful toxin, tetanospasmin. The toxin impairs the nerves that control your muscles (motor neurons).

All these statements are correct. Hence, your answer will be option [D].